Semiconductor device with silicide cap

Abstract

A semiconductor device includes a substrate, an epi-layer, an etch stop layer, an interlayer dielectric (ILD) layer, a silicide layer cap and a contact plug. The substrate has a first portion and a second portion neighboring to the first portion. The etch stop layer is disposed on the second portion. The ILD layer is disposed on the etch stop layer. The silicide cap is disposed on the epi-layer. The contact plug is disposed on the silicide cap and surrounded by the ILD layer.

What is claimed is: 
     
       1. A semiconductor device, comprising:
 a substrate with a first portion and a second portion neighboring to the first portion; 
 an epi-layer disposed on the first portion; 
 an etch stop layer disposed on the second portion; 
 an interlayer dielectric (ILD) layer disposed on the etch stop layer, 
 a silicide cap disposed on the epi-layer; and 
 a contact plug disposed on the silicide cap and surrounded by the ILD layer; and 
 a silicide layer between the contact plug and the ILD layer. 
 
     
     
       2. The semiconductor device of  claim 1 , wherein the silicide cap is formed from titanium silicide, nickel silicide, cobalt silicide, platinum silicide, palladium silicide, tungsten silicide, tantalum silicide or erbium silicide. 
     
     
       3. The semiconductor device of  claim 1 , wherein the contact plug comprises aluminum (Al), tungsten (W), or copper (Cu). 
     
     
       4. The semiconductor device of  claim 1 , wherein the epi-layer is formed from silicon or silicon-germanium. 
     
     
       5. The semiconductor device of  claim 1 , wherein the epi-layer is a source/drain region or a gate. 
     
     
       6. The semiconductor device of  claim 1 , further comprising a liner between the contact plug and the ILD layer. 
     
     
       7. The semiconductor device of  claim 6 , wherein the silicide layer is between the contact plug and the liner. 
     
     
       8. The semiconductor device of  claim 6 , wherein the liner is formed from silicon nitride, silicon oxy-nitride, silicon carbide or silicon oxy-carbide. 
     
     
       9. A method for fabricating a semiconductor device, comprising:
 providing a substrate with a first portion and a second portion neighboring to the first portion; 
 forming an epi-layer on the first portion; 
 forming an etch stop layer on the second portion; 
 forming an ILD layer on the etch stop layer and the epi-layer; 
 etching the ILD layer on the first portion to form a contact opening for exposing the epi-layer; 
 forming a silicide cap on the epi-layer through the contact opening; and 
 filling the contact opening with a contact plug. 
 
     
     
       10. The method of  claim 9 , wherein the operation of filling the contact opening comprises filling the contact opening with the contact plug formed from Al, W or Cu. 
     
     
       11. The method of  claim 9 , wherein the operation of forming the silicide cap comprises:
 forming a silicon layer on the ILD layer and the epi-layer, and conformal to the contact opening; 
 annealing the silicon layer to form the silicide cap on the epi-layer and a silicide layer on the ILD layer and conformal to the contact opening; and 
 removing the silicide layer on the ILD layer. 
 
     
     
       12. The method of  claim 11 , wherein the operation of forming the silicide cap comprises etching the silicide layer conformal to the contact opening. 
     
     
       13. The method of  claim 11 , wherein the operation of removing the silicide layer comprises removing the silicide layer on the ILD layer using a chemical mechanical polishing (CMP) process. 
     
     
       14. The method of  claim 11 , wherein the operation of forming the silicon layer comprises forming the silicon layer on the ILD layer and the epi-layer, and conformal to the contact opening using a chemical vapor deposition (CVD) process, a physical vapor deposition (PVD) process or a high density plasma (HDP) process. 
     
     
       15. The method of  claim 9 , further comprising forming a liner on the ILD layer and conformal to the contact opening. 
     
     
       16. The method of  claim 15 , wherein the operation of forming the silicide cap comprises:
 forming a silicon layer conformal to the liner and on the epi-layer; 
 annealing the silicon layer to form a silicide cap on the epi-layer and a silicide layer on the liner; and 
 removing the silicide layer and the liner above the ILD layer. 
 
     
     
       17. The method of  claim 16 , wherein the operation of forming the silicide cap comprises etching the silicide layer on the liner conformal to the contact opening. 
     
     
       18. The method of  claim 16 , wherein the operation of removing the silicide layer and the liner comprises removing the silicide layer and the liner above the ILD layer using a CMP process. 
     
     
       19. The method of  claim 16 , wherein the operation of forming the silicon layer comprises forming the silicon layer conformal to the liner and on the epi-layer using a CVD process, a PVD process or a HDP process.